Selecting with a mouse click

On occasion we are having users use the F4 option to look up material and when they select the material, with a left mouse click, the first item in the list is selected instead. It seams the only sure way to make this stop is to have them reboot their computer. A work around people can select the material, they want to select, is use the arrow keys,highlight the material, and then press enter.

The File version we are currently on is 6404.4.14.1012 Build 784994 Patch 14